Lead locating fixture



Jan. 28,1941. w. RICHTER 2,414,896

LEAD LOCATING FIXTURE Filed July 27, 1945 3 Sheets-Sheet l I N V E/Y TOR. WLZZLQWMZ I Jan. 28, 1947. w. RICHTER LEAD LOCATING FIXTURE Filed July 27, 1945 I 5 Sheets-Sheet 2 INVENTQR. ZULZZaZJW Jul. 28, 1947. w. RICHTER LEAD LOCATING FIXTURE 3 Sheets-Sheet 3 Filed July 27, 1945 INVENTOR.

Patented Jan. 28, 1947 LEAD LOCATING FIXTURE William Richter, Kankakee, Ill., assignor to Para mount Textile Machinery 00., Kankakee, 111., a corporation of Illinois Application July 27, 1945, Serial No. 607,359

This invention relates to improvements in lead locating fixtures adapted for use in connection with the operation of thread grinding machines and the like for picking up the lead of previously ground or cut threads so that the threads may be reground with accuracy and precision.

It frequently is necessary to regrind threaded pieces which have previously been threaded by grinding or cutting operations for the purpose of removing burrs, chatter marks or other imperfections, which may be present either because of defects in their original formation or on account of damage resulting from use, or for the purpose of finishing the grinding to the desired pitch diameter or of reducing the pitch diameter of previously formed threads.

The principal object of the present invention is to provide an improved fixture by the use of which the lead of a thread in relation to the center or chamfer of the work piece and the driver may be located with an accuracy within one ten-thousandth of an inch, thus permitting the original threads to be further ground with great precision.

until its end or center reaches a predetermined position, which has previously been determined by reference to a master work piece and which may be shown by an indicator, and then securing in a predetermined angular position on the work piece to be reground a driving dog adapted to be engaged by the driving member of the thread grinding machine to which the work piece is then transferred. Other objects relate to various features of construction and arrangement which will appear more fully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which one embodiment of the invention is illustrated. In the drawings,

Figure 1 shows a partial side elevation of a por tion of a thread grinding machine illustrating the head stock, tail stock, driving member and cutting and grinding tool;

Fig. 2 shows a sectional view taken on the line 2-2 of Fig. 1;

13 Claims. (Cl. 51-277) Fig. 3 shows a partial plan view of the lefthand portion of the machine illustrated in Fig. 1, showing the head stock and the driving dog;

Fig. 4 is a perspective view of a work piece having the driving dog secured thereon;

Fig. 5 shows a top plan view of the improved lead locating fixture with a work piece mounted therein;

Fig. 6 shows a side elevation of the fixture illustrated in Fig. 5;

Fig. 7 shows an end elevation of the left-hand end of the device illustrated in Figs. 5 and 6; and

Fig. 8 shows an end elevation or the right-hand end of the device shown in Figs. 5 and 6.

In Fig. 1 of the drawings, there is illustrated a portion of a thread grinding machine comprising the grinding member [0 having mounted thereon the head stock H and the driving member l2. The head stock II is provided with the usual center recess ll to receive one end of the work piece although it will be understood that it might be provided with a projectin center pin to engage a corresponding recess in the work piece. The tail stock 13 is similarly provided with a, center recess l3 to receive the other end of the work piece and this tail stock is carried in the usual fashion by the head M. The grinding wheel I5 is adapted to grind the threads li -which are formed in the work piece [6 adjacent to the tail piece l3. On the opposite end portion of the work piece [-6 there is mounted a driving dog [8 which is formed as a split member embracing the work piece and adapted to be clamped thereon by a threaded stud I9. The driving dog 18 has a projecting lug l8 which is adapted to extend between the arms I2 of the drivin member, as shown in Fig. 2, being secured in position by a set screw 20. In this way, the driving member 12, carried by the rotatable head I 0, is adaptedto impart rotation to the work piece [-6 through the driving dog I8, thus rotating the work piece dur-' support adjacent to the grinding machine or upon a part of the'grinding machine and it carries the partsby which the lead of the thread on a work 'piece is located and fixed with respect to the l driving dog l8 before the work piece andthe drivof studs 28 and which has slidably and rotatably mounted therein a spindle 29 upon one end of which there is fixed a chuck 3B which is similar in size and formation to the tail piece 13 in that it has a recess 3i provided with tapered annular walls similar to the recess Id for receiving the threaded end of the work piece It. A coil spring 3! is mounted between the chuck 30 and the block 21 and normally tends to move the spindle 29 and the chuck 30 toward the left as viewed in Figs. and 6, this movement being limited by the engagement with the block 2! of a collar 33 which i secured on the righthand end of the spindle 29 by a setscrew 34 so that it normally engages the faceof the block 27 under the influence of the spring 3|.

At the right or" the block 21, as viewed in Figs. 5 and 6, there i located an indicator 35 which is carried by a bracket 35 having on its under side an undercut groove 36 shown in Fig, 8, which slidably en.gages,;the outwardly flaring guideway 23 formed upon the bed or base 2 5. A setscrew 31 engages one side of the bracket 35 and enters a recess in. a shim 38 which may be pressed against the side of the guideway 25 by the adjustment of the screw 3? for the purpose of securing the bracket 35 and the indicator 35 in adjusted position longitudinally of the fixture. The indicator 35 has graduations 35 over which a pointer 35 is adapted to move and this pointer is actuated by a plunger 35 which extends endwise from the casing of the indicator in axial alignment with the axis of the spindle 26. The graduations 35* are carried by a dial 535 which is rotatable on the casing of the indicator and which is normally held by friction in adjusted position, this being a wellknown form of indicator now in commercial use.

At the other end of the bed or base 25, there is mounted a block db which is provided on its under side with an undercut groove 40 engaged by the guideway 25 formed on the upper part of the base and. this block is adapted to be secured in adjusted position on the base 26 by setscrews M engaging a, threaded aperture in the side of the undercut groove in the block and entering a recess in a shim 32 which is adapted to be pressed against the side of the guideway by the adjustment of the screw. An arm 44 is hinged at one end on the block 4 as shown at 45, and the complementary parts 4 5* and 6t of a split nut 46, threaded to receive the threaded end of the work piece It, are secured to the block 60; and the arm 44, retpectively, by the studs 4'2, as shown particularly in Fig. '7. At the end thereof opposite the hinge pin the block 40 carries an eye-bolt 48 which is pivoted thereon at 49 and which is adapted to engage a U-shaped slot M formed in the free end of the arm M. A win nut 5!) engages the threaded end of the eye-bolt 48 and when the threaded portion of the work piece I6 is in place between the parts of the split nut 46, the wing nut may be tightened in order to regulate the frictional resistance to the turning of the Work piece in the split nut.

-In the operation of this device, a master work iece I6 which has been accurately formed in the .grinding machine and which still has the driving .48 of the split nut and with the arm 44 swung upwardly out of position, the two threaded por- -tions being mated in such relationship to each other that the collar 33 on the spindle 29 will be moved away from the face of the blockZl. Having thus located the master work piece, the arm 44 is moved downwardly and is secured in place by the eye-bolt 48 and the wing nut 52!, the wing nut being tightened to put a slight friction on the threads to resist the turning of the work piece. The lug l8' on the dog i 8 fixed on the maste work piece is then moved downwardly against a stop screw 5! which is mounted in a thread recess formed in the base 26 and which is adapted to be secured in adjusted position by a lock nut 52. The indicator bracket 36 is then adjusted on the guideway 26 of the base 26 to 'Iluse the plunger 35 to engage the end of the spindle 29 with sufilcient pressure to move the pointer 35 3, portion of a revolution from its normal position. After the indicator has been secured in this position by the tightening of the setscrew 31, the dial 35 is turned to locate the pointer 35* at the zero graduation 35 The parts of the fixture have now been adjusted to determine the characteristics of the master work piece it which has thus been located in the fixture.

After making this preliminary setting of the parts of the fixture with respect to the master work piece, a threaded work piece it of the same size and formation as the master work piece, but having threads which require regrinding, i placed in the fixture in the manner previously described but with a driving dog I3 thereon in loose posi tion,

When placing this new work piece in the fixture, the threads thereof do not have any definite setting with respect to those of the split nut 48 but after the parts of the nut have been closed the eye-bolt 48 is SWLllig upwardly and the wing nut 58 is tightened to apply friction to the threads of the work piece. After this has been done, the work piece is rotated by hand in a counterclockwise direction until the pointer 35 of the indicator is again brought back to the zero position on the dial, which zero position was determined by adjusting the dial when the master work piece was in the fixture. Having thus adjusted the work piece, the driving dog if! thereon is rotated until its lug it engages the top of the stop screw El and its setscrew I9 is then tightened to secure the driving dog in that position on the work piece. The parts have now been adjusted to correspond to the relative positions of the corresponding parts when the-master work piece was in the fixture and the new work piece may then be removed from the fixture and placed in the grinding machine to be rotated by the driving member 52 and cperated upon by the grinding wheel I5 with the certainty that the threads it of the new work piece will be reground with accuracy and precision in conformity with the lead of the threads which were originally formed therein.

Although one example of the new method of loeating the lead of a threaded member and one embodiment of the new lead locating fixture have been illustrated and described, it will be understood that the invention may be constructed in various other embodiments which come within the scope of. the appended claims.

I claim:

1. A lead locating fixture comprising a nut mounted in fixed position for receiving a correspondingly threaded end portion of a work piece, a spindle mounted in a fixed bearing for endwise movement with respect to said nut and having at one end thereof a part adapted to support and position axially the end of the work piece opposite said threaded portion, and mean for indi- '5 eating the endwise position of said spindle when it is engaged by the work piece.

2. A lead locating fixture comprising a nut mounted in fixed position for receiving a correspondingly threaded end portion of a work piece, a spindle mounted in a fixed bearing for endwise movement with respect to said nut and having at one end thereof a part adapted to support and position axially the end of the work piece opposite said threaded portion, means for indicating the endwise position of said spindle when it is engaged by the work piece, and means for locating a driving dog in fixed angular position on said work piece,

3. A lead locating fixture comprising a base, a nut mounted in fixed position on said base for receiving a correspondingly threaded end portion of a work piece, a spindle mounted for endwise movement on said base and having a part to support and position axially the opposite end portion of the work piece, an indicator mounted on said base and having an operating part engageable by the end of said spindle, and a driving dog adapted to be secured on said work piece.

i. A lead locating fixture comprising a base, a nut mounted in fixed position on said base for receiving a correspondingly threaded end portion of a work piece, a spindle mounted for endwise movement on said base and having a part to support and position axially the opposite end portion of the work piece, an indicator mounted on said base and having an Operating part engageable by the end of said spindle, a driving dog adapted to be secured on said work piece, and means for predetermining the angular position of said driving dog on said work piece.

5. A lead locating fixture comprising a threaded member engageable by the threaded end portion of a work piece, a member movable axially of said work piece and having a partadapted to engage and support the opposite end portion of said work piece, and means for indicating the endwise position of said axially movable member.

6. A lead locating fixture comprising a threaded member engageable by the threaded end portion of a work piece, a member movable axially of said work piece and having a part adapted to engage and support the opposite end portion of said work piece, an indicator adapted to be actuated by endwise movement of said axially movable member when said work piece is placed in said fixture, and means for adjusting the indication of said indicator for a predetermined work piece.

'7. A lead locating fixture comprising a threaded member engageable by the threaded end portion of a work piece, a member movable axially of said work piece and having a part adapted to engage and support the opposite end portion of said work piece, means for indicating the endwise position of said axially movable member, a driving dog adapted to be clamped on said work piece, and means for determining the angular position of said driving dog when said driving dog is clamped on said work piece.

8. A lead locating fixture comprising a threaded member engageable by the threaded end portion of a work piece, a member movable axially of said work piece and having a part adapted to engage and sup-port the opposite end portion of said work piece, an indicator adapted to be actuated by endwise movement of said axially movable member when said work piece is placed in said fixture, means for adjusting the indication of said indicator for a predetermined work piece, a driving dog adapted to be clamped on said work piece, and means for determining the angular position of said driving dog when said driving dog is clamped on said work piece.

9. A lead locating fixture comprising a split nut mounted in fixed position and engageable by the threaded end portion of a work piece, a relatively fixed bearing, a spindle mounted for endwise movement in said bearing and having a part adapted to position and support'the other end of said work piece, and means normally moving'said spindle toward said work piece.

10. A lead locating fixture comprising a split nut mounted in fixed position, said nut having a hinged part movable away from the remainder of the nut to permit the insertion of the threaded end portion of a work piece, means for adjustably clamping said hinged part on said threaded portion, and means engageable with the other end of said work piece for indicating and recording the position of said work piece in said nut.

11. A lead locating fixture comprising a split nut mounted in fixed position, said nut having a hinged part movable away from the remainder of the nut to permit the insertion of the threaded end portion of a work piece, means for adjustably clamping said hinged part on said threaded portion, a spindle for resiliently engaging the other end of the work piece, and an indicator actuated by the endwise movement of said spindle away from said nut.

12. A lead locating fixture comprising a split nut mounted in fixed position, said nut having a hinged part movable away from the remainder of the nut to permit the insertion of the threaded end portion of a work piece, means for adjustably clamping said hinged part on said threaded portion, a spindle for resiliently engaging the other 1 end of the work piece, an indicator actuated by the endwise movement of said spindle away from said nut, and means for adjusting said indicator to give a predetermined indication when a master work piece is in the fixture.

13. The method of locating the lead of a thread in a work piece which comprises the steps of placing the threaded portion of a master work piece in engagement with a threaded member while causing the other end of said master work piece to effect endwise movement of another member, turning said master work piece in said threaded member to cause a driving dog fixed in said work piece to assume a predetermined angular position, then recording the endwise position of said second named member, then removing said master work piece and replacing it by a new work piece to be ground with the threaded portion of the new work piece engaging said threaded member and with the other end thereof engaging said second named member, then turning said new work piece in said threaded mem ber until said second named member reaches said previously mentioned endwise position, and then securing a driving dog on said new work piece in the same angular position as that occupied by said previously mentioned driving dog on said master work piece.

WILLIAM RICHTER. 

